Identify retrospectively (1960-1968) a study population of 250 women with primary inflitrating breast carcinomas 1.1-2.0 cm in diameter also a substantial subset of women with malignant tumors 1 cm or less in diameter. These patients should have been treated by at least a modified radical mastectomy and been found to have negative lymph nodes upon routine examination. Study patients with primary tumors 2 cm or less with positive lymph nodes to provide a basis for comparing the distribution of various features. Institute quality control pathology measures assuring intra- and inter-observer reproducibility. Carry out a detailed pathologic study of the carcinoma, surrounding breast, and axillary lymph nodes in order to describe the morphologic features present. Obtain retrospectively data about certain clinical or epidemilogic factors known to be related to the risk for developing breast carcinoma. Ascertain the ten year follow-up status of the patients entered into the study.